Methods and systems for leaching a metal-bearing material
Methods for recovering a metal value from a metal-bearing material are provided. The method comprises agglomerating the metal-bearing material with an agglomeration solution comprising a raffinate, an oxidant, and citric acid or salts thereof to form an agglomerated metal-bearing material; leaching the agglomerated metal-bearing material with a leaching solution comprising the raffinate and the citric acid or salts thereof to produce a pregnant leaching solution and a leached material; re-oxidizing the leached material with a curing solution comprising the raffinate and the oxidant; and recovering the metal value from the pregnant leach solution to produce the raffinate.
1 . A method for extracting a metal value from a metal-bearing material, comprising:
leaching the metal-bearing material with a leaching solution comprising a raffinate, an oxidant, and citric acid or salts thereof, to produce a first leached material and a first pregnant leach solution, wherein the metal-bearing material comprises the metal value and wherein the oxidant is hydrogen peroxide; and
recovering the metal value from the first pregnant leach solution to produce the metal value and the raffinate;
wherein the metal value is copper.
2 . The method of claim 1 , wherein the first leached material further comprises ferrous (Fe 2+ ) and ferric ions (Fe 3+ ).
3 . The method of claim 2 , further comprising:
curing the first leached material with a curing solution to re-oxidize the ferrous (Fe 2+ ) ions to ferric (Fe 3+ ) ions and produce a cured leached material, wherein the curing solution comprises the raffinate and the oxidant, and wherein the cured leached material comprises the metal value;
leaching the cured leached material with the leaching solution to produce a second leached material and a second pregnant leach solution; and
recovering the metal value from the second pregnant leach solution.
4 . The method of claim 3 , wherein the curing solution further comprises citric acid or salts thereof.
5 . The method of claim 3 , wherein the curing solution comprises a concentration of hydrogen peroxide in a range of about 8% by weight to about 30% by weight.
6 . The method of claim 3 , wherein the curing solution further comprises a concentration of citric acid or salts thereof in the range of about 2 grams per liter to about 10 grams per liter.
7 . The method of claim 3 , wherein the leaching comprises a heap leach operation and the curing comprises a trickle-down cure.
8 . The method of claim 3 , wherein the curing and the leaching may comprise a cycle.
9 . The method of claim 8 , wherein the cycle may be repeated before the step of recovering.
10 . The method of claim 1 , further comprising agglomerating the metal-bearing material with an agglomeration solution before the leaching, wherein the agglomeration solution comprises the raffinate, the oxidant, and citric acid or salts thereof.
11 . The method of claim 10 , wherein the agglomeration solution comprises a concentration of hydrogen peroxide in a range of about 1% to about 6% by weight.
12 . The method of claim 10 , wherein the agglomeration solution comprises a concentration of citric acid or salts thereof in a range of about 2 grams per liter to about 10 grams per liter.
13 . The method of claim 1 , wherein the leaching solution comprises a concentration of citric acid or salts thereof in a range of about 0.1 g/l to about 20 g/l.
14 . The method of claim 1 , wherein the leaching solution comprises a concentration of hydrogen peroxide in a range of about 8% by weight.
15 . The method of claim 1 , wherein the metal-bearing material comprises a primary or secondary copper sulfide, or mixtures thereof.
16 . The method of claim 1 , wherein the leaching comprises a heap leach operation further comprising subsurface injection of the leaching solution into a heap of the heap leach operation.
17 . The method of claim 1 , wherein the leaching solution further comprises a concentration of added air and/or oxygen.